% iron - sulphuric acid pickling - steel wire rod?
% iron - sulphuric acid pickling - steel wire rod?
(OP)
I would like to know if the following testing method for iron % in sulfuric acid - steel wire rod pickling is correct and if any other exist?
first - % acid
- Add 5 mls of acid solution in a 250 mls becker.
- Add 100 mls of water.
- Add 4 drops of methyl orange
- use carbonate sodium until color change to yellow
keep same solution
second - %iron
- add 5 mls of sulfuric acid
- use potassium permaganate until color change (light pink).
NOTE: number of mls (1.on) used of permanganate potassium x 1.44= % iron
thanks
first - % acid
- Add 5 mls of acid solution in a 250 mls becker.
- Add 100 mls of water.
- Add 4 drops of methyl orange
- use carbonate sodium until color change to yellow
keep same solution
second - %iron
- add 5 mls of sulfuric acid
- use potassium permaganate until color change (light pink).
NOTE: number of mls (1.on) used of permanganate potassium x 1.44= % iron
thanks





RE: % iron - sulphuric acid pickling - steel wire rod?
I have added the conversion for sulfuric acid to procedures for hydrochloric acid pickling solution; H+ is H+.
It's probably more common to use sodium hydroxide solution than carbonate solution for acid titrations, but either works as long as you know the normality. The procedure I use for HCl-containing solutions is this:
Hydrochloric (or sulfuric) acid:
1. Pipet a 2 ml sample into a 250 ml beaker and add 100 ml DI water.
2. Add 5 mLs of 20%(w/v) KF (avoids Fe+3 precipitation).
3. Titrate to pH = 3.8 using 1 N NaOH.
[HCl (36 wt%)], vol.% = 4.356 x mls of 1 N NaOH.
or [H2SO4 (98 wt%)], vol.% = 1.33 x mls of 1 N NaOH.
Using a 5-mL sample & methyl orange indicator with 1 N NaOH titrant, the HCl concentration is given as
[HCl (36 wt%)], vol. % = 1.74 x mls of 1 N NaOH
or [HCl (32 wt%)], vol. % = 1.96 x mls of 1 N NaOH
or [H2SO4 (98 wt%)], vol.% = 0.532 x mls of 1 N NaOH.
A 1 N carbonate titrating solution should give the same results.
IRON analysis. Your oxidation titration only gives [Fe+2], not [Fe+3] ( the predominant Fe species present in yellow solutions).
Try adding hydrogen peroxide to a sample to see all Fe as Fe+3, or sodium thiosulfate for entirely Fe+2. Also, I suggest not using wt% unless also measuring the specific gravity (SG).
[Fe+2], g/L = 11.1 x mLs 0.1 N KMnO4 or 1.11 x mLs 1.0 N KMnO4
For total [Fe], you can first titrate all Fe+3 to Fe[sup+2[/sup] by reduction with 0.1 N sodium thiosulfate (no excess, can do by ORP or color), then titrate all the Fe+2 by oxidation with 0.1 N KMnO4. Or, calculate the [Fe+3] from the reduction titration and add it to the [Fe+2] from your original oxidation titration.
Maybe only necessary to do the [Fe+2] analysis as you already have data on the pickling behavior. Also, some people determine [Fe] by careful SG measurement after adjusting both [acid] and temperature to standard values, but this is a bit crude.
RE: % iron - sulphuric acid pickling - steel wire rod?